Sealing means for providing a fluid seal between relatively rotatable elements are generally known to the art. Applicant""s prior U.S. patent application Ser. No. 07/305,416, filed Feb. 1, 1989 (now abandoned) entitled xe2x80x9cSystem For Sealing Relatively Movable Elementsxe2x80x9d discloses a system for providing a fluid seal including a deformable seal, particularly a ring shaped seal element received in a groove of one of two relatively rotatable elements. A resilient element, as for example, a coil spring, is disposed in a groove defined in one relatively rotatable element, and urges the seal element in a direction towards the other relatively rotatable element to provide a fluid-tight seal between the first and second relatively rotatable elements.
The following references were cited in connection with Applicant""s patent application: U.S. Pat. Nos. 1,858,173; 1,986,285; 3,023,014; 3,494,624; 3,525,530; 3,658,350; 3,711,104; 3,887,198; 4,132,417; 4,497,494; 4,711,168; 4,736,586; British Patent Nos. 1,280,712; 6,802; 627,085; French Patent No. 974,917; Canadian Patent No. 585,362; Netherlands Patent No. 24,905; Publication xe2x80x9cUpdating Actuator Piston Ring Seals of Teflon TFExe2x80x9d, by H. A. Traub, The Journal of Teflon, August, 1965; and xe2x80x9cFundamental Principles of Polymeric Materialsxe2x80x9d, by Stephen L. Rosen, published by John Wiley and Sons, 1971.
The aforementioned references disclose systems for providing fluid seals including systems employing either deformable seal elements, resilient supporting elements urging the seal element in a direction to maintain a fluid seal, or both. Sealing systems including deformable seal elements and/or resilient means urging the deformable seal elements into a sealing position, are disadvantageous in many respects. In particular, the use of a deformable seal element and/or resilient means engaging the deformable seal element, results in rapid wear of the seal requiring frequent replacement. Additionally, wear of the seal can result in a malfunction of the overall sealing system causing fluid to flow through the seal.
It is the primary object of the present invention to provide improved sealing means overcoming the disadvantages of the known sealing systems. In particular, the improvement of the present invention includes providing sealing means for relatively rotatable elements comprising a substantially non-deformable seal element used in conjunction with a substantially non-resilient spacer/supporting means. The improvement in accordance with the present invention enables the system to employ a thicker seal element than used in conventional sealing systems, reduces the rate of wear of the seal thereby reducing the frequency of replacement and reducing the likelihood of malfunction of the system, and permits fluid to enhance the integrity of the seal provided by the sealing element. Other advantages of the improved sealing system in accordance with the present invention will become apparent to those skilled in the art from the following discussion.
A system for sealing relatively rotatable elements, and in particular a drum with a hub and a piston, includes a groove defined in one of the rotatable elements adapted to receive a seal element therein. The groove element, which is arcuate in shape, is defined on the periphery of the piston or the hub carried by the drum, both of which are preferably circular in configuration. The seal received in the groove is preferably ring-shaped in configuration, and is formed from a substantially non-deformable material. The width of the seal is preferably less than the width of the groove, and the periphery of one surface of the seal extends beyond the outer surface of the groove.
A supporting or spacer element is received in the groove and is disposed between the groove and the seal element. The supporting or spacer element, which is also generally arcuate in configuration to conform to the shape of the groove and the seal element, is formed from a substantially non-resilient material.
In operation, when one of the rotatable elements rotates relative to the other, the seal element and the supporting (spacer) element maintain a fluid seal as a result of the mass of the two elements, and the rotational forces acting thereon. Because the supporting element is substantially non-resilient and does not urge the seal towards the opposed relatively rotatable element, wear on the seal element is reduced. Moreover, because no positive resilient force acts on the seal urging it towards the opposed relatively rotatable element, and because the seal itself is not formed from a deformable material, the seal element can be thicker than seal elements used in known systems and can be formed from a more rigid material. Accordingly, the integrity of the fluid seal is maintained when one of the relatively rotatable elements is rotated relative to the other, yet wear on the seal is reduced. Because the seal itself is formed from a substantially non-deformable material and is of a width less than the width of the groove, the seal element will not deform to occupy the space remaining in the groove between the seal element and the supporting (spacer) element during relative rotation of the elements. Accordingly, a recessed space will be defined in the groove adjacent to the seal element, and fluid received in this space will apply fluid pressure to the seal element and the supporting (spacer) element in the groove to enhance the integrity of the seal and to maintain the seal element and the supporting (spacer) element in its fixed operating position within the groove to enhance the efficiency of the sealing relationship during relative rotation of the two relatively rotatable elements.